This invention relates to a friction aircraft braking system and more particularly to a new and improved multiple actuator for an aircraft wheel and brake assembly.
During the braking of an aircraft, a plurality of alternately splined stator and rotor discs are brought into sliding frictional engagement with each other generating considerable heat within the braking elements and the supporting structure. The stator and rotor discs, which can be made of metal or carbon, can withstand the high heat build-up in such brakes, with heat shields provided for the adjacent structures to limit heat absorption. For the immediate adjacent structures such as the multiple actuating mechanisms of the plural pistons and their cylinders insulators are used to limit the heat absorption. The supporting structure for the brake actuating pistons and cylinders must be designed to be lightweight as other component parts to enhance the overall need to keep the weight manageable and fuel efficient.
The present invention recognizes that the interfacing between the pressure plate and the forwardly disposed faces of the pistons that are circumferentially spaced around the piston housing are parallel surfaces and that under severe braking forces, they encounter tremendous stress forces that tend to deflect the outer radial portions of the piston housing to cock their corresponding pistons in their respective housings. This action causes side loading and uneven wear of the piston and its supporting structure including the pressure plate. Bending action increases as the brake discs wear and the piston elements must extend axially outward a greater distance for full brake application. The bending action and resultant side loading is especially harmful to assemblies that have automatic adjusters built into the pistons, due to excessive wear on close clearance adjuster components, and increased difficulty in maintaining an effective seal of hydraulic fluid. It is an objective of the present invention to provide means for maintaining the alignment of the forwardly disposed portions of the piston or piston heads with the pressure plate regardless of the piston housing deflection, thereby reducing the effects of side loading. An additional benefit of this construction is improved distribution of actuation force into the heat sink providing more even wear and reduced temperature differential across heat sink wear surfaces. This will improve disk utilization resulting in longer use between overhauls and improved performance for high-energy stops.